1. Field of Invention
The present invention relates to an electro-optical device encased in a mounting case in which an electro-optical device, such as a liquid crystal panel, which is used as a light valve of a projection display apparatus, such as a liquid crystal projector, is accommodated or encased in a mounting case and to a projection display apparatus including the electro-optical device encased in the mounting case.
2. Description of Related Art
In the related art, generally, when a liquid crystal panel is used as a light valve of a liquid crystal projector, the liquid crystal panel is not provided in an exposed state on a console, etc., constituting the liquid crystal projector, but it is accommodated or encased in a suitable mounting case, and then the mounting case including the liquid crystal panel is provided on the console. Herein, the liquid crystal panel can be easily attached and fixed to the console by suitable screw holes provided in the mounting case.
In the liquid crystal projector, the light emitted from a light source is projected on the liquid crystal panel encased in the mounting case as focused light. Light passing through the liquid crystal panel is enlarged and projected on the screen to display images. In such a liquid crystal projector, since the enlarged projection is generally predetermined, relatively intensive light emitted from a light source, such as a metal halide lamp is used.
According to this constitution, first, there is a problem in which the temperature of the liquid crystal panel in the mounting case rises. The rise in temperature causes the rise in temperature of the liquid crystal interposed between a pair of transparent substrates in the liquid crystal panel. Therefore, the characteristics of the liquid crystal are deteriorated. In addition, when the light emitted from the source light is uneven, the liquid crystal panel is partially heated, and then the deviation of its transmittance is generated by the so-called hot spots. Thus, the quality of projected images deteriorates.
Techniques for preventing the rise in temperature of the liquid crystal panel include an approach for preventing the rise in temperature of the liquid crystal panel by providing a heat radiating sheet between the liquid crystal panel and a heat radiating plate in a liquid crystal display module including the liquid crystal panel and a package for holding and accommodating the liquid crystal panel and for having the heat radiating plate.
In addition, in order to address the problem, other approaches, such as an approach of providing a light shielding film on a substrate located at the side of the liquid crystal panel on which light is incident and an approach of using the mounting case made of a light reflective material, in which the liquid crystal panel is held or accommodated, have been known.
However, the related art approaches for preventing the rise in temperature of the liquid crystal panel have the following problems. As long as intensive light is emitted from the light source, the problem of the rise in temperature of the liquid crystal panel may occur at any time. Therefore, in order to obtain still higher image quality, more effective measures to prevent the rise in temperature are required instead of or in addition to the aforementioned approaches.
Further, there is the following difficulty for each approach for preventing the rise in temperature as described above.
According to the approach of using the above-described heat radiating sheet, while it may be thought that heat accumulation in a liquid crystal panel can effectively radiate outward, there is no effective action to decide a position of the liquid crystal panel in a package. Specifically, using the heat radiating sheet, while the rise in temperature of the liquid crystal panel will definitely cause the rise in temperature of the package, it may be thought that the dislocation of liquid crystal panel in the package occurs due to the difference in coefficients of linear expansion between the heat radiating sheet and the package.
Moreover, when it is assumed that the heat radiating plate or the heat radiating sheet is provided to cover the whole surface of a substrate, they may be useless for a transmissive liquid crystal panel although being useful for a reflective liquid crystal panel.
In addition, according to the approach of reflecting light by the light shielding film and the mounting case, as the areas of the light shielding film and the mounting case increase, the amount of the reflected light increases. Thus, the rise in temperature of the liquid crystal panel can be reduced or prevented. However, if the amount of the reflected light increases indiscriminately, the stray light increases in the housing for accommodating the liquid crystal panel in the mounting case. Thus, the quality of images can be deteriorated. In addition, since the increase of the area of the light shielding film causes the reduction of the amount of the light from the source light, which is to be originally incident to and to pass through the liquid crystal panel, the image can be dark. Thus, it is contrary to the aforementioned purpose in which the intensive light source is used in order to display brighter image. Accordingly, the aforementioned related art approaches do not have solutions for the above problems.